The California Highway Patrol and Pacifica police responded to a report of a possibly deceased person near state Route 35 and Sharp Park Road at around 1:35 a.m., police said.
Arriving officers found a male who was declared dead at the scene.
While officers were conducting an investigation, a motorist arrived at the scene and said he had struck a person walking in the roadway.
The suspect, San Bruno resident Leopoldo Tobilla, 57, was determined to have been driving under the influence of alcohol and was arrested for DUI resulting in fatal injury, leaving the scene of a collision that had resulted in a fatal injury and vehicular manslaughter.
He was taken to San Mateo County jail in Redwood City. Anyone who might have witnessed the crash is asked to contact Pacifica police at (650) 738-7314.